/*
** $Id: llex.c,v 2.63 2013/03/16 21:10:18 roberto Exp $
** Lexical Analyzer
** See Copyright Notice in lua.h
*/


#include <locale.h>
#include <string.h>

#define llex_c
#define LUA_CORE

#include "lua.h"

#include "lctype.h"
#include "ldo.h"
#include "llex.h"
#include "lobject.h"
#include "lparser.h"
#include "lstate.h"
#include "lstring.h"
#include "ltable.h"
#include "lzio.h"



#define next(ls) (ls->current = zgetc(ls->z))



#define currIsNewline(ls)	(ls->current == '\n' || ls->current == '\r')


/* ORDER RESERVED */
static const char *const luaX_tokens [] = {
	"and", "break", "do", "else", "elseif",
	"end", "false", "for", "function", "goto", "if",
	"in", "local", "nil", "not", "or", "repeat",
	"return", "then", "true", "until", "while",
	"..", "...", "==", ">=", "<=", "~=", "::", "<eof>",
	"<number>", "<name>", "<string>"
};


#define save_and_next(ls) (save(ls, ls->current), next(ls))


static l_noret lexerror (LexState *ls, const char *msg, int token);


static void save (LexState *ls, int c) {
	Mbuffer *b = ls->buff;
	if (luaZ_bufflen(b) + 1 > luaZ_sizebuffer(b)) {
		size_t newsize;
		if (luaZ_sizebuffer(b) >= MAX_SIZET/2)
			lexerror(ls, "lexical element too long", 0);
		newsize = luaZ_sizebuffer(b) * 2;
		luaZ_resizebuffer(ls->L, b, newsize);
	}
	b->buffer[luaZ_bufflen(b)++] = cast(char, c);
}


void luaX_init (lua_State *L) {
	int i;
	for (i=0; i<NUM_RESERVED; i++) {
		TString *ts = luaS_new(L, luaX_tokens[i]);
		luaS_fix(ts);  /* reserved words are never collected */
		ts->tsv.extra = cast_byte(i+1);  /* reserved word */
	}
}


const char *luaX_token2str (LexState *ls, int token) {
	if (token < FIRST_RESERVED) {  /* single-byte symbols? */
		lua_assert(token == cast(unsigned char, token));
		return (lisprint(token)) ? luaO_pushfstring(ls->L, LUA_QL("%c"), token) :
			luaO_pushfstring(ls->L, "char(%d)", token);
	}
	else {
		const char *s = luaX_tokens[token - FIRST_RESERVED];
		if (token < TK_EOS)  /* fixed format (symbols and reserved words)? */
			return luaO_pushfstring(ls->L, LUA_QS, s);
		else  /* names, strings, and numerals */
			return s;
	}
}


static const char *txtToken (LexState *ls, int token) {
	switch (token) {
	case TK_NAME:
	case TK_STRING:
	case TK_NUMBER:
		save(ls, '\0');
		return luaO_pushfstring(ls->L, LUA_QS, luaZ_buffer(ls->buff));
	default:
		return luaX_token2str(ls, token);
	}
}


static l_noret lexerror (LexState *ls, const char *msg, int token) {
	char buff[LUA_IDSIZE];
	luaO_chunkid(buff, getstr(ls->source), LUA_IDSIZE);
	msg = luaO_pushfstring(ls->L, "%s:%d: %s", buff, ls->linenumber, msg);
	if (token)
		luaO_pushfstring(ls->L, "%s near %s", msg, txtToken(ls, token));
	luaD_throw(ls->L, LUA_ERRSYNTAX);
}


l_noret luaX_syntaxerror (LexState *ls, const char *msg) {
	lexerror(ls, msg, ls->t.token);
}


/*
** creates a new string and anchors it in function's table so that
** it will not be collected until the end of the function's compilation
** (by that time it should be anchored in function's prototype)
*/
TString *luaX_newstring (LexState *ls, const char *str, size_t l) {
	lua_State *L = ls->L;
	TValue *o;  /* entry for `str' */
	TString *ts = luaS_newlstr(L, str, l);  /* create new string */
	setsvalue2s(L, L->top++, ts);  /* temporarily anchor it in stack */
	o = luaH_set(L, ls->fs->h, L->top - 1);
	if (ttisnil(o)) {  /* not in use yet? (see 'addK') */
		/* boolean value does not need GC barrier;
		table has no metatable, so it does not need to invalidate cache */
		setbvalue(o, 1);  /* t[string] = true */
		luaC_checkGC(L);
	}
	L->top--;  /* remove string from stack */
	return ts;
}


/*
** increment line number and skips newline sequence (any of
** \n, \r, \n\r, or \r\n)
*/
static void inclinenumber (LexState *ls) {
	int old = ls->current;
	lua_assert(currIsNewline(ls));
	next(ls);  /* skip `\n' or `\r' */
	if (currIsNewline(ls) && ls->current != old)
		next(ls);  /* skip `\n\r' or `\r\n' */
	if (++ls->linenumber >= MAX_INT)
		luaX_syntaxerror(ls, "chunk has too many lines");
}


void luaX_setinput (lua_State *L, LexState *ls, ZIO *z, TString *source,
					int firstchar) {
						ls->decpoint = '.';
						ls->L = L;
						ls->current = firstchar;
						ls->lookahead.token = TK_EOS;  /* no look-ahead token */
						ls->z = z;
						ls->fs = NULL;
						ls->linenumber = 1;
						ls->lastline = 1;
						ls->source = source;
						ls->envn = luaS_new(L, LUA_ENV);  /* create env name */
						luaS_fix(ls->envn);  /* never collect this name */
						luaZ_resizebuffer(ls->L, ls->buff, LUA_MINBUFFER);  /* initialize buffer */
}



/*
** =======================================================
** LEXICAL ANALYZER
** =======================================================
*/



static int check_next (LexState *ls, const char *set) {
	if (ls->current == '\0' || !strchr(set, ls->current))
		return 0;
	save_and_next(ls);
	return 1;
}


/*
** change all characters 'from' in buffer to 'to'
*/
static void buffreplace (LexState *ls, char from, char to) {
	size_t n = luaZ_bufflen(ls->buff);
	char *p = luaZ_buffer(ls->buff);
	while (n--)
		if (p[n] == from) p[n] = to;
}


#if !defined(getlocaledecpoint)
#define getlocaledecpoint()	(localeconv()->decimal_point[0])
#endif


#define buff2d(b,e)	luaO_str2d(luaZ_buffer(b), luaZ_bufflen(b) - 1, e)

/*
** in case of format error, try to change decimal point separator to
** the one defined in the current locale and check again
*/
static void trydecpoint (LexState *ls, SemInfo *seminfo) {
	char old = ls->decpoint;
	ls->decpoint = getlocaledecpoint();
	buffreplace(ls, old, ls->decpoint);  /* try new decimal separator */
	if (!buff2d(ls->buff, &seminfo->r)) {
		/* format error with correct decimal point: no more options */
		buffreplace(ls, ls->decpoint, '.');  /* undo change (for error message) */
		lexerror(ls, "malformed number", TK_NUMBER);
	}
}


/* LUA_NUMBER */
/*
** this function is quite liberal in what it accepts, as 'luaO_str2d'
** will reject ill-formed numerals.
*/
static void read_numeral (LexState *ls, SemInfo *seminfo) {
	const char *expo = "Ee";
	int first = ls->current;
	lua_assert(lisdigit(ls->current));
	save_and_next(ls);
	if (first == '0' && check_next(ls, "Xx"))  /* hexadecimal? */
		expo = "Pp";
	for (;;) {
		if (check_next(ls, expo))  /* exponent part? */
			check_next(ls, "+-");  /* optional exponent sign */
		if (lisxdigit(ls->current) || ls->current == '.')
			save_and_next(ls);
		else  break;
	}
	save(ls, '\0');
	buffreplace(ls, '.', ls->decpoint);  /* follow locale for decimal point */
	if (!buff2d(ls->buff, &seminfo->r))  /* format error? */
		trydecpoint(ls, seminfo); /* try to update decimal point separator */
}


/*
** skip a sequence '[=*[' or ']=*]' and return its number of '='s or
** -1 if sequence is malformed
*/
static int skip_sep (LexState *ls) {
	int count = 0;
	int s = ls->current;
	lua_assert(s == '[' || s == ']');
	save_and_next(ls);
	while (ls->current == '=') {
		save_and_next(ls);
		count++;
	}
	return (ls->current == s) ? count : (-count) - 1;
}


static void read_long_string (LexState *ls, SemInfo *seminfo, int sep) {
	save_and_next(ls);  /* skip 2nd `[' */
	if (currIsNewline(ls))  /* string starts with a newline? */
		inclinenumber(ls);  /* skip it */
	for (;;) {
		switch (ls->current) {
		case EOZ:
			lexerror(ls, (seminfo) ? "unfinished long string" :
				"unfinished long comment", TK_EOS);
			break;  /* to avoid warnings */
		case ']': {
			if (skip_sep(ls) == sep) {
				save_and_next(ls);  /* skip 2nd `]' */
				goto endloop;
			}
			break;
				  }
		case '\n': case '\r': {
			save(ls, '\n');
			inclinenumber(ls);
			if (!seminfo) luaZ_resetbuffer(ls->buff);  /* avoid wasting space */
			break;
				   }
		default: {
			if (seminfo) save_and_next(ls);
			else next(ls);
				 }
		}
	} endloop:
	if (seminfo)
		seminfo->ts = luaX_newstring(ls, luaZ_buffer(ls->buff) + (2 + sep),
		luaZ_bufflen(ls->buff) - 2*(2 + sep));
}


static void escerror (LexState *ls, int *c, int n, const char *msg) {
	int i;
	luaZ_resetbuffer(ls->buff);  /* prepare error message */
	save(ls, '\\');
	for (i = 0; i < n && c[i] != EOZ; i++)
		save(ls, c[i]);
	lexerror(ls, msg, TK_STRING);
}


static int readhexaesc (LexState *ls) {
	int c[3], i;  /* keep input for error message */
	int r = 0;  /* result accumulator */
	c[0] = 'x';  /* for error message */
	for (i = 1; i < 3; i++) {  /* read two hexadecimal digits */
		c[i] = next(ls);
		if (!lisxdigit(c[i]))
			escerror(ls, c, i + 1, "hexadecimal digit expected");
		r = (r << 4) + luaO_hexavalue(c[i]);
	}
	return r;
}


static int readdecesc (LexState *ls) {
	int c[3], i;
	int r = 0;  /* result accumulator */
	for (i = 0; i < 3 && lisdigit(ls->current); i++) {  /* read up to 3 digits */
		c[i] = ls->current;
		r = 10*r + c[i] - '0';
		next(ls);
	}
	if (r > UCHAR_MAX)
		escerror(ls, c, i, "decimal escape too large");
	return r;
}


static void read_string (LexState *ls, int del, SemInfo *seminfo) {
	save_and_next(ls);  /* keep delimiter (for error messages) */
	while (ls->current != del) {
		switch (ls->current) {
		case EOZ:
			lexerror(ls, "unfinished string", TK_EOS);
			break;  /* to avoid warnings */
		case '\n':
		case '\r':
			lexerror(ls, "unfinished string", TK_STRING);
			break;  /* to avoid warnings */
		case '\\': {  /* escape sequences */
			int c;  /* final character to be saved */
			next(ls);  /* do not save the `\' */
			switch (ls->current) {
			case 'a': c = '\a'; goto read_save;
			case 'b': c = '\b'; goto read_save;
			case 'f': c = '\f'; goto read_save;
			case 'n': c = '\n'; goto read_save;
			case 'r': c = '\r'; goto read_save;
			case 't': c = '\t'; goto read_save;
			case 'v': c = '\v'; goto read_save;
			case 'x': c = readhexaesc(ls); goto read_save;
			case '\n': case '\r':
				inclinenumber(ls); c = '\n'; goto only_save;
			case '\\': case '\"': case '\'':
				c = ls->current; goto read_save;
			case EOZ: goto no_save;  /* will raise an error next loop */
			case 'z': {  /* zap following span of spaces */
				next(ls);  /* skip the 'z' */
				while (lisspace(ls->current)) {
					if (currIsNewline(ls)) inclinenumber(ls);
					else next(ls);
				}
				goto no_save;
					  }
			default: {
				if (!lisdigit(ls->current))
					escerror(ls, &ls->current, 1, "invalid escape sequence");
				/* digital escape \ddd */
				c = readdecesc(ls);
				goto only_save;
					 }
			}
read_save: next(ls);  /* read next character */
only_save: save(ls, c);  /* save 'c' */
no_save: break;
				   }
		default:
			save_and_next(ls);
		}
	}
	save_and_next(ls);  /* skip delimiter */
	seminfo->ts = luaX_newstring(ls, luaZ_buffer(ls->buff) + 1,
		luaZ_bufflen(ls->buff) - 2);
}


static int llex (LexState *ls, SemInfo *seminfo) {
	luaZ_resetbuffer(ls->buff);
	for (;;) {
		switch (ls->current) {
		case '\n': case '\r': {  /* line breaks */
			inclinenumber(ls);
			break;
				   }
		case ' ': case '\f': case '\t': case '\v': {  /* spaces */
			next(ls);
			break;
				  }
		case '-': {  /* '-' or '--' (comment) */
			next(ls);
			if (ls->current != '-') return '-';
			/* else is a comment */
			next(ls);
			if (ls->current == '[') {  /* long comment? */
				int sep = skip_sep(ls);
				luaZ_resetbuffer(ls->buff);  /* `skip_sep' may dirty the buffer */
				if (sep >= 0) {
					read_long_string(ls, NULL, sep);  /* skip long comment */
					luaZ_resetbuffer(ls->buff);  /* previous call may dirty the buff. */
					break;
				}
			}
			/* else short comment */
			while (!currIsNewline(ls) && ls->current != EOZ)
				next(ls);  /* skip until end of line (or end of file) */
			break;
				  }
		case '[': {  /* long string or simply '[' */
			int sep = skip_sep(ls);
			if (sep >= 0) {
				read_long_string(ls, seminfo, sep);
				return TK_STRING;
			}
			else if (sep == -1) return '[';
			else lexerror(ls, "invalid long string delimiter", TK_STRING);
				  }
		case '=': {
			next(ls);
			if (ls->current != '=') return '=';
			else { next(ls); return TK_EQ; }
				  }
		case '<': {
			next(ls);
			if (ls->current != '=') return '<';
			else { next(ls); return TK_LE; }
				  }
		case '>': {
			next(ls);
			if (ls->current != '=') return '>';
			else { next(ls); return TK_GE; }
				  }
		case '~': {
			next(ls);
			if (ls->current != '=') return '~';
			else { next(ls); return TK_NE; }
				  }
		case ':': {
			next(ls);
			if (ls->current != ':') return ':';
			else { next(ls); return TK_DBCOLON; }
				  }
		case '"': case '\'': {  /* short literal strings */
			read_string(ls, ls->current, seminfo);
			return TK_STRING;
				  }
		case '.': {  /* '.', '..', '...', or number */
			save_and_next(ls);
			if (check_next(ls, ".")) {
				if (check_next(ls, "."))
					return TK_DOTS;   /* '...' */
				else return TK_CONCAT;   /* '..' */
			}
			else if (!lisdigit(ls->current)) return '.';
			/* else go through */
				  }
		case '0': case '1': case '2': case '3': case '4':
		case '5': case '6': case '7': case '8': case '9': {
			read_numeral(ls, seminfo);
			return TK_NUMBER;
				  }
		case EOZ: {
			return TK_EOS;
				  }
		default: {
			if (lislalpha(ls->current)) {  /* identifier or reserved word? */
				TString *ts;
				do {
					save_and_next(ls);
				} while (lislalnum(ls->current));
				ts = luaX_newstring(ls, luaZ_buffer(ls->buff),
					luaZ_bufflen(ls->buff));
				seminfo->ts = ts;
				if (isreserved(ts))  /* reserved word? */
					return ts->tsv.extra - 1 + FIRST_RESERVED;
				else {
					return TK_NAME;
				}
			}
			else {  /* single-char tokens (+ - / ...) */
				int c = ls->current;
				next(ls);
				return c;
			}
				 }
		}
	}
}


void luaX_next (LexState *ls) {
	ls->lastline = ls->linenumber;
	if (ls->lookahead.token != TK_EOS) {  /* is there a look-ahead token? */
		ls->t = ls->lookahead;  /* use this one */
		ls->lookahead.token = TK_EOS;  /* and discharge it */
	}
	else
		ls->t.token = llex(ls, &ls->t.seminfo);  /* read next token */
}


int luaX_lookahead (LexState *ls) {
	lua_assert(ls->lookahead.token == TK_EOS);
	ls->lookahead.token = llex(ls, &ls->lookahead.seminfo);
	return ls->lookahead.token;
}

